Method of casting dished items



Dec. 4, 1962 J. K. PENNELL, JR 3,066,376 METHOD OF CASTING DISHED ITEMS Filed April 17, 1961 IN VEN TOR.

JAMES 1r. PE/V/VEL 1.,Jr.

HIS ATTORNEYS United States Patent ()fiice 3,066,376 METHOD OF CASTING DISHED ITEMS James K. Pennell, Jr., 217 (Pverhill Road, Orinda, Calif. Filed Apr. 17, 1961, Ser. No. 103,422 2 (Zlainis. (Cl. 25-455) My invention relates to the field of casting and more particularly to the method of casting dished items of cement, concrete or like material.

Among the objects of my invention are:

(1) To provide a novel and improved method of casting of dished items;

(2) To provide a novel and improved method for the casting of dished items, which will inherently impart symmetry thereto;

(3) To provide a novel and improved method for the casting of dished items, which will facilitate the removing of the cast item from the mold;

(4) To provide a novel and improved method of casting a dished item which method permits of substantial leeway in determining depth and bottom characteristics of the cast item;

(5) To provide a novel and improved method of casting a dished item, with a minimum of equipment;

(6) To rovide a novel and improved method of casting a dished item, in which method the cavity is formed by natural forces.

Additional objects of my invention will be brought out in the following description of a preferred embodiment of the same, taken in conjunction with the accompanying drawing wherein:

FIG. 1 is a three dimensional view depicting the essentials of the present invention;

FIG. 2 is a view in section through the embodiment depicted in FIG. 1, and showing the same in the first stage of casting an item;

FIG. 3 is a view in section corresponding to that of FIG. 2, but depicting a subsequent stage in the casting of an item;

FIG. 4 is a view in section through an item prepared in accordance with the present invention.

Referring to the drawings for details of my invention in its preferred form, the same involves a form 1 comprising a frame 3 having a contour corresponding to the contour of the item to be cast, while spanning the lower edges of the frame, is a bottom 5 of elastic material such as rubber or the like, sufiiciently thin to permit of stretching under the weight of material from which the item is to be cast.

The form is placed upon a hard surface such as a tabletop 7 or equivalent, and the material 9, out of which the item is to be cast, is poured into the form to approximately the thickness desired in the finished item 11. Such material should be of the character of cement, concrete or the like, which when mixed is semi-liquid in character, but which, after a short period of time, begins to set prior to hardening.

In accordance with the method involved in the present invention, as such material begins to set and reaches a consistency which can assume and retain a spherical surface, the frame is lifted or otherwise separated from the hard surface on which it rests, and the material, in response to such separation, will sag, causing the material to assume a dished form, this being permitted by the elastic bottom of the form. The extent of separation of the frame from the surface on which it previously rested, will determine the depth of the item, and if lifted sufliciently to clear the bottom, the bottom of the item will lie in a spherical surface.

By not lifting the frame sufiiciently to clear the bottom of the form, the center portion of the bottom will remain in contact with the hard surface, and accordingly form a fiat planar bottom to the dished item, which in most cases will be the desired result. It will be appreciated further, that the area of the bottom may be readily controlled by the extent of separation between the frame and the hard surface.

As an inherent feature of the present invention, it may be pointed out that when the frame is separated from the surface upon which it rested, the material in the process of setting, is more solid than semi-liquid, and consequently, the edges 13 of the item will, during the sagging period, tend to swing away from the walls of the frame, along the lines indicated in FIG. 3 of the drawings. The significance of this lies in the fact that the item, when ready for removal from the form, will present no problem of sticking or adhering to the walls of the frame, but will fall out readily upon tilting the form sufficiently.

The spacing of the frame from the surface upon which it previously rested, can be accomplished by lifting the same manually and resting it upon blocks of proper size, whereby the same spacing will be obtained in each instance, and an exact duplicate of the item created, or in lieu thereof, the form may be connected to a block and tackle 17 (partially illustrated) including strands or ropes 19 anchored at uniformly spaced points around the frame 3. When employing a block and tackle, the frame may be left suspended at the proper spacing from the supporting surface, until hardening of the cast item is realized, or the frame may be raised sufiiciently to permit insertion of the spacer blocks, and then lowered to rest upon the blocks.

Should one desire an internal curvature or contour differing from that which would form naturally, a suitably shaped core may be impressed into the material during setting and hardening.

From the foregoing description of my invention in its preferred form, it will be apparent that the same fulfills all the objects attributed thereto, and while I have illustrated and described the same in its preferred form, I do not desire to be limited in my protection to the specific details and method illustrated and described, except as may be necessitated by the appended claims.

I claim:

1. The method of casting a dished item from material adapted to set from a semi-liquid condition prior to hardening, said method comprising pouring said material in its semi-liquid condition into a form comprising a frame and an elastic bottom, and while said form rests on a solid surface, and when said material has set sufiiciently to assume and retain a spherical surface, separating said frame from said solid surface to efiect a sagging of said elastic bottom, then maintaining said separation until said material has hardened.

2. The method of casting a dished item from material adapted to set from a semi-liquid condition prior to References Cited in the file of this patent UNITED STATES PATENTS Cross May 8, Hewett May 19, Schaaf Apr. 25, Tomlinson Feb. 13, Ripley Mar. 5, Brownell May 26, MacMillan Nov. 8, 

